JP4389620B2 - Electrostatic latent image developing toner, electrostatic latent image developing developer, and image forming method - Google Patents

Description

  The present invention relates to an image forming method applied to developing an electrostatic latent image formed by electrophotography, electrostatic recording, or the like, an electrostatic image developing toner used therefor, and an electrostatic image developing developer. .

  A method of visualizing image information through an electrostatic charge image such as electrophotography is currently used in various fields. In electrophotography, an electrostatic charge image is formed on a photoreceptor by charging and exposure processes, the electrostatic latent image is developed with a developer containing toner, and visualized through a transfer and fixing process.

  As the toner, emulsion polymerization aggregation that intentionally controls the shape and surface structure of the toner, as compared with the toner based on the kneading and pulverization method, which has a relatively wide particle size distribution and an irregular shape, so that the performance maintenance is not sufficient. A method for producing toner by the method has been proposed. (For example, JP-A-63-2822752, JP-A-6-250439)

  In the emulsion polymerization aggregation method, a resin dispersion is generally prepared by emulsion polymerization or the like, while a colorant dispersion in which a colorant is dispersed in a solvent is prepared, and the resin dispersion and the colorant dispersion are mixed. This is a manufacturing method in which aggregated particles corresponding to the volume average particle diameter of the toner are formed and then heated to fuse and coalesce the aggregated particles to form a toner. Further, the toner is free from the inner layer to the surface layer. Means for realizing more precise particle structure control by performing control have been proposed (for example, Japanese Patent No. 3141784).

  These toners can be easily reduced in diameter and precise particle structure control has been realized, so that the image quality of conventional electrophotographic images has been dramatically improved and high reliability can be achieved at the same time. Yes.

  For example, shape controllability can be given as an example of particle structure control, and it is now possible to align the toner to an appropriate shape. Became possible.

  On the other hand, in recent years, the volume average particle size of toner particles has been decreasing due to demands for high image quality such as fine line reproducibility and low image density portion reproducibility. This indicates that in the development process, which is a pre-process of the transfer process, toner development on the latent image on the photoreceptor surface tends to be difficult from the viewpoint of electrostatic adhesion between toner particles and carrier particles. The transfer tends to be difficult due to an increase in the adhesion between the toner particles and the photoreceptor.

  Although it is necessary to reduce the charge amount of the toner particles themselves in order to improve the developability and transferability of the toner, the toner with a low charge amount causes problems such as fogging during development, and at the same time shortens the life of the developer. This causes problems such as On the other hand, when the charge amount of the toner is increased, not only the image density is lowered during the development, but also the transfer force becomes more difficult because the adhesion force with the photosensitive member is increased.

  In the transfer process, a non-contact type transfer device such as corotron is known as the transfer device. However, the non-contact type has an advantage of simple mechanism and low cost and is widely used. However, there are known problems associated with the generation of ozone and other discharge products due to the discharge phenomenon. For example, the discharge product may adhere to and contaminate the surface of the photoconductor, thereby obstructing the formation of a latent image on the surface of the photoconductor, thereby causing problems such as image loss on the photoconductor. In addition, since the transfer method using the non-contact type requires a stable high voltage power supply, regular cleaning is performed for adhesion of toner, silicone oil, and other discharge products to the corotron wire, There are various problems such as the need for maintenance such as replacement at the time of disconnection.

Based on the above, the bias roll type transfer system, so-called contact type, which can reduce the generation cost of ozone by reducing the generation of ozone and maintenance, mainly for small printers for personal use. Many types are being used.
In the contact type transfer method, since the transfer electric field is formed by the contact between the transfer material and the bias roll, unlike the non-contact type, in order to transfer the toner on the photoreceptor onto the transfer material. However, an appropriate pressure is required between the bias roll and the photoreceptor, and the pressure is approximately 5 g / cm or more in terms of linear pressure.

  As a result of the pressure applied between the photoconductor and the bias roll, a pressure is also applied between the transfer material passing between them and the photoconductor, and at the same time, the pressure is applied to the developed image on the photoconductor. As a result, the toner particles constituting the developed image are aggregated, and as a result, problems such as a decrease in transfer efficiency occur.

  The above-mentioned contact transfer method is easily affected by the toner charge amount distribution (sometimes referred to as electrostatic adhesion) at the time of transfer. There is a tendency that it is more difficult to use the combination of the two.

  In order to solve this problem, a method has been proposed in which various assistants are externally added to the toner particles as means for increasing the transfer efficiency to reduce the adhesion between the surface of the photoreceptor and the toner particles. For example, in JP-A-61-23160, JP-A-63-11875, JP-A-2-1870, JP-A-2-90175, etc., external addition of inorganic compounds such as silica, titania, alumina, etc. Is being considered. The methods described in these methods use a hard inorganic fine powder as a spacer agent to improve transfer efficiency, and although there are some effects, as described above, the adhesion of toner to the photoreceptor by the pressure of contact transfer. The effect on transfer due to state fluctuation is not sufficient, and the addition of external additives makes the toner particles themselves non-uniform in charge level, fogging during transfer, and reduction in charge amount due to transfer of external additives to the carrier, etc. This is not enough because it leads to secondary damage.

  Japanese Patent Application Laid-Open No. 63-279264 discloses a method in which a mixed fine powder of a fatty acid metal salt and a resin is externally added and the auxiliary agent is stably supplied without being subjected to high stress. Although this method can assist transfer to some extent, the resin component in the mixed fine powder adheres to the photoconductor, making transfer difficult and further difficult to clean. The effect is insufficient because there are secondary obstacles such as adhesion to the surface of the body and damage to the surface of the photoreceptor.

  JP-A-3-121462 and JP-A-8-38854 propose addition of fine powder treated with silicone oil or silicone varnish, and JP-A-7-255583 proposes addition of fine silicone resin particles. However, it is insufficient because it tends to become highly charged due to long-term use and / or long-term storage in a low-temperature and low-humidity environment, resulting in poor transfer and image density.

In addition, sulfonic acid is added to the binder resin of the toner to secure the charge amount, and the addition of metal oxide helps to increase the charging speed of the resin, thereby suppressing the difference in charge amount between the toner particles. A measure for avoiding defects has also been proposed (for example, JP-A-2002-268285). However, although this method provides some support for the charging speed, it is not sufficient particularly from the viewpoint of reducing the particle size of the toner particles themselves, and causes a problem that secondary obstacles such as fog cannot be avoided completely. .
Japanese Patent Laid-Open No. 63-282275 JP-A-6-250439 Japanese Patent No. 3141784 Japanese Patent Laid-Open No. 61-23160 JP 63-11875 A Japanese Patent Laid-Open No. 2-1870 JP-A-2-90175 JP-A-63-279264 Japanese Patent Laid-Open No. 3-121462 JP-A-8-38854 JP-A-7-255583, JP 2002-268285 A

  As described above, the contact transfer method using a bias roll has several advantages, and a technique using this is expected even when a small particle size toner is used.

Therefore, this invention makes it a subject to achieve the following objectives. That is, an object of the present invention is to develop an electrostatic latent image developing toner capable of maintaining both efficient transfer performance and high cleaning performance over a long period of time, even when a small particle size toner, which has been difficult in the past, is used, and It is to provide a developer for developing an electrostatic latent image. Another object of the present invention is to provide an image forming method that does not reduce transfer efficiency due to aggregation between toner particles, particularly in a transfer system having a bias roll transfer system.

The above problem is solved by the following means. That is, the present invention
1. In an electrostatic latent image developing toner containing at least toner particles and an external additive excluding silica ,
The external additive is two kinds of additives including titanium compound A and titanium compound B,
The toner particles have a volume average particle size of 4 μm to 8 μm, a GSD showing a volume particle size distribution of 1.23 or less, and a shape factor SF1 of 110 to 140 .
The toner for developing an electrostatic latent image, wherein the titanium compound A and the titanium compound B satisfy the following conditions.
Condition (1): RA <RB
Condition (2): DA <DB
Condition (3): RA ≦ 12.0
(Where RA and RB are the powder resistivity LogE (Ω · cm) when the applied voltage of the titanium compound A and the titanium compound B is 1.0 ^3.8 (V / cm), DA and DB are the titanium compound A and The volume average particle diameter (nm) of the titanium compound B is shown.)
Condition a: Pa ≦ 7
Condition b: Pb ≦ 40
Condition c: Pc ≧ 50
(Wa is the content (wt%) of titanium compound A, WB is the content (wt%) of titanium compound B, and a is the ultrasonic vibration (output 20 W, frequency: 20 kHz) in the toner dispersion. The amount of titanium compound desorbed from the toner particles when given for a minute, b is the amount of titanium compound desorbed from the toner particles when ultrasonic vibration (output 60 W, frequency: 20 kHz) is given for 30 minutes in the toner dispersion, and c is a and b indicate the amount of fine particles remaining on the toner particles after desorption, and Pa = 100 × a / (WA + WB), Pb = 100 × b / (WA + WB), and Pc = 100 × c / (WA + WB). is there.)

2. A latent image forming step for forming an electrostatic latent image on at least the surface of the latent image carrier, and a developer containing at least a toner, and developing the electrostatic latent image formed on the surface of the latent image carrier to develop a toner developed image An image forming process including: a developing process for forming a toner image; a process for transferring a toner image formed on the surface of the latent image carrier onto a recording medium; and a fixing process for thermally fixing the toner image transferred on the surface of the recording medium. In the method
The toner includes at least toner particles and an external additive excluding silica ,
The toner particles have a volume average particle size of 4 μm to 8 μm, a GSD showing a volume particle size distribution of 1.23 or less, and a shape factor SF1 of 110 to 140,
In the image forming method, the titanium compound A and the titanium compound B satisfy the following conditions.
Condition (1): RA <RB
Condition (2): DA <DB
Condition (3): RA ≦ 12.0
(Where RA and RB are the powder resistivity LogE (Ω · cm) when the applied voltage of the titanium compound A and the titanium compound B is 1.0 ^3.8 (V / cm), DA and DB are the titanium compound A and The volume average particle diameter (nm) of the titanium compound B is shown.)
Condition a: Pa ≦ 7
Condition b: Pb ≦ 40
Condition c: Pc ≧ 50
(Wa is the content (wt%) of titanium compound A, WB is the content (wt%) of titanium compound B, and a is the ultrasonic vibration (output 20 W, frequency: 20 kHz) in the toner dispersion. The amount of titanium compound desorbed from the toner particles when given for a minute, b is the amount of titanium compound desorbed from the toner particles when ultrasonic vibration (output 60 W, frequency: 20 kHz) is given for 30 minutes in the toner dispersion, and c is a and b indicate the amount of fine particles remaining on the toner particles after desorption, and Pa = 100 × a / (WA + WB), Pb = 100 × b / (WA + WB), and Pc = 100 × c / (WA + WB). is there.)

2-1. The transferring step is preferably a transferring step directly using a bias roll.

3. In the developer for developing an electrostatic latent image, which includes a toner including at least toner particles and an external additive, and a carrier.
The toner includes at least toner particles and an external additive excluding silica ,
The toner particles have a volume average particle size of 4 μm to 8 μm, a GSD showing a volume particle size distribution of 1.23 or less, and a shape factor SF1 of 110 to 140,
The developer for developing an electrostatic latent image, wherein the titanium compound A and the titanium compound B satisfy the following conditions.
Condition (1): RA <RB
Condition (2): DA <DB
Condition (3): RA ≦ 12.0
(Where RA and RB are the powder resistivity LogE (Ω · cm) when the applied voltage of the titanium compound A and the titanium compound B is 1.0 ^3.8 (V / cm), DA and DB are the titanium compound A and It is a volume average particle size (nm) of the titanium compound B.
Condition a: Pa ≦ 7
Condition b: Pb ≦ 40
Condition c: Pc ≧ 50
(Wa is the content (wt%) of titanium compound A, WB is the content (wt%) of titanium compound B, and a is the ultrasonic vibration (output 20 W, frequency: 20 kHz) in the toner dispersion. The amount of titanium compound desorbed from the toner particles when given for a minute, b is the amount of titanium compound desorbed from the toner particles when ultrasonic vibration (output 60 W, frequency: 20 kHz) is given for 30 minutes in the toner dispersion, and c is a and b indicate the amount of fine particles remaining on the toner particles after desorption, and Pa = 100 × a / (WA + WB), Pb = 100 × b / (WA + WB), and Pc = 100 × c / (WA + WB). is there.)

  According to the present invention, an electrostatic latent image developing toner capable of maintaining both efficient transfer performance and high cleaning performance over a long period of time, even when using a toner having a small particle diameter, which has been difficult in the past, and electrostatic A developer for developing a latent image can be provided. In particular, even in a transfer system having a bias roll transfer system, it is possible to provide an image forming method that does not reduce transfer efficiency due to aggregation between toner particles.

The present invention will be described in detail below.
The electrostatic latent image developing toner of the present invention controls the toner particle size distribution and the shape factor SF1, and at the same time uses two titanium compounds as external additives to improve charge exchange, so that the toner is contained in the developing machine. Even when the toner is newly added, the carrier is quickly charged, and charge exchange with other already charged toner is improved. In addition, by obtaining a toner having a narrow particle size distribution and a narrow charge amount distribution by controlling the toner shape by narrowing the toner particle size distribution, it is possible to maintain both efficient transferability and high cleaning performance over a long period of time. it can.

  Further, even with a transfer system using a bias roll, it is possible to obtain an image forming method that does not reduce transfer efficiency due to aggregation between toner particles.

  More specifically, a titanium compound having a larger volume average particle size of two types of titanium compounds (titanium compound A and titanium compound B) having different volume average particle sizes uses a titanium compound having a higher powder resistivity, and By using a toner having a GSD representing a particle size distribution of 1.23 or less and a shape factor SF1 of 110 to 140, a toner having a high charge exchange property and a narrow charge amount distribution and a narrow particle size distribution can be obtained, and at the same time, a bias roll is used. Even in the transfer system used, a toner with high transfer efficiency can be obtained.

  In particular, in the two-component developer, the toner is conveyed into the developing machine by an auger or the like and added to the developer. At that time, only the portion that can be contacted with the carrier is charged on the toner surface. On the other hand, there is already charged toner inside the developing machine due to stirring with the carrier, and the toner has changed surface properties, specifically the adhesion state of external additives, etc. due to stirring. The developer is charged with the added toner to form a developer having a wide charge amount distribution that deviates from the original design. The developer is developed and visualized on the latent image on the photoconductor in the development area on the developing machine. However, in the case of a developer having a wide charge amount distribution, a toner with a high charge amount is difficult to develop and has a low charge. The amount of toner may cause problems such as adhesion to the surface of the photoreceptor other than the latent image. In general, toner having a larger volume average particle size tends to be developed more easily, but in the case of a toner having a small particle size, the fluidity as a developer is lowered, so the stirring efficiency with the carrier is lowered. In addition, the toner may be destroyed by stirring, and the charge amount distribution tends to be wider.

  In the transfer process, the toner developed on the surface of the photoconductor is transferred in the transfer region. Characteristic values that greatly affect the ease of transfer at this time include toner charge amount, volume average particle diameter, and shape. . As described above, since a toner with a high charge amount and / or a small particle size is difficult to develop in the development process, the transferred toner has a slightly low charge amount and a slightly large particle size, both of which are advantageous for the transfer process. However, the toner having a small particle size has a large toner area in contact with the surface of the photoconductor compared with the surface area of the toner, and therefore, transfer is difficult and the shape of the toner is indefinite. Since the contact area increases, transfer becomes more difficult. In particular, when the toner has a convex portion, as described above, charging easily occurs with the convex portion of the toner that easily comes into contact with the carrier, so that the toner adheres strongly to the photoconductor, and transfer becomes more difficult.

  In addition, small-diameter toner is more likely to aggregate between toner particles, and is easily aggregated by a strong pressure such as a bias roll, thereby reducing transfer efficiency.

  Therefore, in the toner of the present invention, the particle size distribution is controlled by setting GSD to 1.23 or less, the amount of coarse powder and fine powder is controlled, the difference in charge amount between toner particles is reduced, and the shape of the toner is simultaneously By controlling the coefficient SF1 to 110 to 140, surface irregularities are reduced, and the charge amount distribution inside the toner particles is controlled. Furthermore, by using two kinds of titanium compounds having different volume average particle diameters and powder resistivity as external additives, developability and transferability can be improved. Generally, silica, titania or the like is used as an external additive. Although silica can improve the charge amount, the charge amount distribution also tends to increase. On the other hand, titania has a small increase in charge amount but can narrow the charge amount distribution. Two kinds of titanium compounds with different volume average particle diameters are added, and the uneven distribution of the charge amount in the toner particles is reduced by the small particle diameter titanium compound having high powder resistivity and high charge exchange property. By using the titanium compound, the charge exchange between the carrier toner and the toner-toner is improved, and at the same time, the large particle size titanium compound is difficult to be embedded in the toner surface, and the small particle size titanium compound is stirred. Therefore, the toner having an appropriate charge exchange property can be retained for a long period of time.

The powder resistivity of the titanium compound is such that the powder resistivity LogE (Ω · cm) at an applied voltage of 1.0 ^3.8 (V / cm) is 12 or less for the small particle size titanium compound A, and the large particle size titanium compound. The powder resistivity of B needs to be higher than the powder resistivity of the small particle size titanium compound A. The reason for this is not clear, but the development property is small unless the uneven distribution of the charge amount on the toner particle surface is first reduced by the small particle size titanium compound A, and then charge exchange between the toner particles and the toner particles and between the toner particles and the carrier is not performed. The transferability does not improve, and for this purpose, the relationship between the volume average particle diameter and the powder resistivity of the two types of titanium compounds in the present invention is essential.

  The toner of the present invention may be used in any transfer system in the transfer process, but is particularly suitable for a transfer system using a bias roll, which has been difficult in the past. In the transfer method, as described above, since a transfer current is simultaneously applied while applying pressure to the developed image, it is necessary to maintain an appropriate volume resistivity.

  Since the toner of the present invention has the same toner shape and particle size distribution, the resistance of the developed image tends to be uniform and tends to be strong against pressure. It is estimated that this is because there is an effect of suppressing an excessive decrease in resistance due to the small particle size titanium compound A having a resistance smaller than that of the large particle size titanium compound B.

  The toner of the present invention is not particularly limited as long as it is a method capable of forming toner particles having a GSD representing a volume particle size distribution of 1.23 or less and a shape factor SF1 in the range of 110 to 140, but is particularly preferable. This is an emulsion polymerization aggregation method.

  In the emulsion polymerization aggregation method, a resin particle dispersion in which resin particles having a volume average particle diameter of 1 μm or less are dispersed, a colorant dispersion in which a colorant is dispersed, and the like are mixed, and the resin particles and the colorant are mixed with the toner volume average particle diameter. A process of aggregating the particles (hereinafter sometimes referred to as an “aggregation process”), a process of heating the resin particles to a temperature higher than the glass transition point of the resin particles to fuse and coalesce the aggregates to form toner particles (hereinafter referred to as the “fusion process”). ”).

  In the aggregation step, the resin particle dispersion, the colorant dispersion, and, if necessary, the particles in the release agent dispersion are aggregated to form aggregated particles. The agglomerated particles are formed by heteroaggregation or the like. For the purpose of stabilizing the agglomerated particles and controlling the particle size / particle size distribution, the ionic surfactant having a polarity different from that of the agglomerated particles, or a monovalent or more monovalent metal salt or the like is used. A charged compound is added.

  In the fusion step, the resin particles in the aggregated particles are melted at a temperature condition equal to or higher than the glass transition point, and the aggregated particles change from an indeterminate shape to a spherical shape. At this time, the shape factor SF1 of the aggregated particles is 150 or more. However, the shape factor SF1 can be controlled by stopping the heating of the toner when the shape factor SF1 is reached. Thereafter, the agglomerates are separated from the aqueous medium, and washed and dried as necessary to form toner particles.

  As a method for producing the toner of the present invention, a suspension polymerization method can also be preferably used. In the suspension polymerization method, colorant particles, release agent particles and the like are suspended in an aqueous medium to which a dispersion stabilizer and the like are added together with a polymerizable monomer as required, and a desired particle size and particle size distribution are obtained. In this method, the polymerizable monomer is polymerized by means of heating or the like, and then the polymer is separated from the aqueous medium, and washed and dried as necessary to form toner particles.

  As a method for producing the toner of the present invention, a solution suspension granulation method can also be used. In the dissolution suspension granulation method, a polymerizable monomer, a polymerization initiator, a release agent, and magnetic metal fine particles are dispersed in a polymer solution in which a polymerizable monomer is preliminarily polymerized. In the presence of an inorganic or organic dispersant, a mechanical shearing force is applied to suspend the mixture, and then a polymerizable monomer is polymerized by applying thermal energy while applying stirring shear to obtain toner particles. It is a manufacturing method.

  As a method for producing the toner of the present invention, a dissolution suspension method can also be used. In the dissolution suspension method, a solution in which a binder resin, a release agent, a colorant, and the like are dissolved in an organic solvent is suspended by applying a mechanical shear force in the presence of an inorganic or organic dispersant, In this method, toner particles are obtained by removing the solvent.

  As a method for producing the toner of the present invention, a solution emulsion aggregation coalescence method can be used. The dissolution emulsification aggregation coalescence method is a method in which a solution in which a binder resin is dissolved in an organic solvent is desolvated by emulsifying mechanical shearing force in the presence of an anionic surfactant or the like, and a resin of at least 1 μm or less. After obtaining the fine particles, the step of cooling below the glass transition temperature of the binder resin to prepare a resin fine particle dispersion solution, the resin fine particle dispersion solution, a colorant fine particle dispersion in which the colorant fine particles are dispersed, and An aggregating step of mixing the release agent fine particle dispersion in which the release agent fine particles are dispersed to form aggregated particles of the resin fine particles, the colorant fine particles and the release agent fine particles, and the aggregated particles, the glass transition point or melting point of the resin fine particles This is a manufacturing method having a fusion / unification step of fusing and uniting by heating to the above temperature.

  Among these methods, the emulsion polymerization aggregation method is most suitable from the viewpoints of controllability of the particle size distribution and controllability of the toner shape. The reason is that since there is no shearing force during granulation, there is little generation of coarse and fine powder, and the toner shape can be controlled from an irregular shape to a spherical shape.

  As specific examples of the binder resin used in the toner of the present invention, known resin materials can be used. For example, styrenes such as styrene, parachlorostyrene, and α-methylstyrene: methyl acrylate, acrylic acid Vinyl such as ethyl, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate Esters having a group: Vinyl nitriles such as acrylonitrile and methacrylonitrile: Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether: Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone: Ethylene, Examples include homopolymers of monomers such as polyolefins such as propylene and butadiene, copolymers obtained by combining two or more of these, and mixtures thereof, and epoxy resins, polyester resins, and polyurethane resins. , Polyamide resins, cellulose resins, polyether resins, etc., non-vinyl condensation resins, mixtures of these with the vinyl resins, and graft polymers obtained when polymerizing vinyl monomers in the presence of them Is mentioned.

  Among these, styrene-alkyl acrylate copolymers and styrene-alkyl methacrylate copolymers are particularly preferable.

  In the toner of the present invention, in order to improve the chargeability with the carrier, a dissociative vinyl monomer may be contained together with the monomer constituting the binder resin when the binder resin is polymerized. Examples of the dissociative vinyl monomer include acrylic acid, methacrylic acid, maleic acid, cinnamic acid, fumaric acid, vinyl sulfonic acid, ethyleneimine, vinylpyridine, vinylamine and other polymer acids and polymer base materials. Any of the monomers can be used. Polymer acids are preferred because of the ease of polymer formation reaction, among others, dissociable vinyl monomers having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, cinnamic acid, fumaric acid, etc. It is preferable from the viewpoint of controllability. In addition, these dissociative vinyl monomers can be used by copolymerizing usually at the time of binder resin polymerization.

  In the toner of the present invention, a chain transfer agent can be used during the polymerization of the binder resin. Although there is no restriction | limiting in particular as a chain transfer agent, The compound which has a thiol component can be used. Specifically, alkyl mercaptans such as hexyl mercaptan, heptyl mercaptan, octyl mercaptan, nonyl mercaptan, decyl mercaptan, and dodecyl mercaptan are preferred, and in particular, the molecular weight distribution is narrow, so that the storage stability of the toner at high temperature is improved. preferable.

A cross-linking agent may be added to the binder resin in the present invention as necessary. Specific examples of such crosslinking agents include aromatic polyvinyl compounds such as divinylbenzene and divinylnaphthalene; divinyl phthalate, divinyl isophthalate, divinyl terephthalate, divinyl homophthalate, divinyl trimesate / trivinyl, naphthalene dicarboxylate Polyvinyl esters of aromatic polyvalent carboxylic acids such as divinyl acid and diphenyl biphenyl carboxylate; Divinyl esters of nitrogen-containing aromatic compounds such as divinyl pyridine dicarboxylate; Vinyl pyromutate, vinyl furan carboxylate, pyrrole-2- Vinyl esters of unsaturated heterocyclic compounds such as vinyl carboxylate and vinyl thiophenecarboxylate; butanediol methacrylate, hexanediol acrylate, octanediol methacrylate, decanediol acrylate (Meth) acrylic acid esters of linear polyhydric alcohols such as dodecanediol methacrylate; branches such as neopentylglycol dimethacrylate and 2-hydroxy-1,3-diacryloxypropane; ) Acrylic acid esters; Polyethylene glycol di (meth) acrylate, Polypropylene polyethylene glycol di (meth) acrylates; Divinyl succinate, divinyl fumarate, vinyl / divinyl maleate, divinyl diglycolate, vinyl / divinyl itaconate, acetone Divinyl dicarboxylate, divinyl glutarate, divinyl 3,3′-thiodipropionate, trans-aconite divinyl / trivinyl, divinyl adipate, divinyl pimelate, divinyl suberate, dibi azelate Le, sebacate, divinyl dodecanedioate divinyl, the polyvinyl esters of polycarboxylic acids such as oxalic acid, divinyl; and the like.

  These crosslinking agents may be used alone or in combination of two or more. Among the above crosslinking agents, as the crosslinking agent in the present invention, (meth) acrylic acid esters of linear polyhydric alcohols such as butanediol methacrylate, hexanediol acrylate, octanediol methacrylate, decanediol acrylate, and dodecanediol methacrylate are used. Branched chains such as neopentyl glycol dimethacrylate and 2-hydroxy-1,3-diacryloxypropane, (meth) acrylic acid esters of substituted polyhydric alcohols; polyethylene glycol di (meth) acrylate, polypropylene polyethylene glycol di ( It is preferable to use (meth) acrylates.

  The content of the crosslinking agent is preferably in the range of 0.05 to 5% by weight, more preferably in the range of 0.1 to 1.0% by weight, based on the total amount of polymerizable monomers.

  The resin used in the toner of the present invention can be produced by radical polymerization of a polymerizable monomer. There is no restriction | limiting in particular as an initiator for radical polymerization used here. Specifically, hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide Ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, tert-butyl hydroperoxide pertriphenyl acetate, tert-butyl formate, Peroxides such as tert-butyl peracetate, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl permethoxyacetate, tert-butyl perN- (3-toluyl) carbamate, 2,2 '-Azobisp Bread, 2,2′-dichloro-2,2′-azobispropane, 1,1′-azo (methylethyl) diacetate, 2,2′-azobis (2-amidinopropane) hydrochloride, 2,2 ′ -Azobis (2-amidinopropane) nitrate, 2,2'-azobisisobutane, 2,2'-azobisisobutyramide, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2- Methyl methylpropionate, 2,2′-dichloro-2,2′-azobisbutane, 2,2′-azobis-2-methylbutyronitrile, dimethyl 2,2′-azobisisobutyrate, 1,1′-azobis (1 -Sodium methylbutyronitrile-3-sulfonate), 2- (4-methylphenylazo) -2-methylmalonodinitrile, 4,4'-azobis-4-cyanovaleric acid, 3,5-dihy Roxymethylphenylazo-2-methylmalonodinitrile, 2- (4-bromophenylazo) -2-allylmalonodinitrile, 2,2′-azobis-2-methylvaleronitrile, 4,4′-azobis-4 -Dimethyl cyanovalerate, 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobiscyclohexanenitrile, 2,2'-azobis-2-propylbutyronitrile, 1,1 ' -Azobis-1-chlorophenylethane, 1,1'-azobis-1-cyclohexanecarbonitrile, 1,1'-azobis-1-cycloheptanenitrile, 1,1'-azobis-1-phenylethane, 1,1 '-Azobiscumene, 4-nitrophenylazobenzylcyanoacetate ethyl, phenylazodiphenylmethane, phenylazotriphenylmeta 4-nitrophenylazotriphenylmethane, 1,1′-azobis-1,2-diphenylethane, poly (bisphenol A-4,4′-azobis-4-cyanopentanoate), poly (tetraethylene glycol) -2,2'-azobisisobutyrate) and the like, 1,4-bis (pentaethylene) -2-tetrazene, 1,4-dimethoxycarbonyl-1,4-diphenyl-2-tetrazene and the like Can be mentioned.

  Known colorants can be used as the colorant used in the toner of the present invention. Examples of pigments include carbon black, copper oxide, black titanium oxide, black iron hydroxide, manganese dioxide, aniline black, activated carbon, magnetic powder such as nonmagnetic ferrite, magnetic ferrite, and magnetite, aniline blue, calcoil blue, and chromium. Yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be exemplified as a representative one.

  As the colorant, a dye can be used. Examples of the dye that can be used include various dyes such as basic, acidic, dispersed, and direct dyes, such as nigrosine. Moreover, these can be used individually or in mixture, and also in the state of a solid solution.

  These colorants are dispersed by a known method, and for example, a rotary shear type homogenizer, a media type dispersing machine such as a ball mill, a sand mill, or an attritor, a high-pressure opposed collision type dispersing machine, or the like is preferably used.

  Since the colorant is a surfactant having polarity and is dispersed in the aqueous system by the homogenizer, the colorant is selected from the viewpoint of dispersibility in the toner. The added amount of the colorant can be 3 to 50 parts by weight with respect to 100 parts by weight of the binder resin.

  Examples of the release agent used in the toner of the present invention include low molecular weight polyolefins such as polyethylene, polypropylene and polybutene: silicones having a softening point by heating: oleic acid amide, erucic acid amide, ricinoleic acid amide, stearic acid amide, etc. Fatty acid amides such as: carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil etc. Plant waxes: animal waxes such as beeswax: montan wax, ozokerite, ceresin, paraffin wax, microcrystalline Examples thereof include minerals such as waxes, Fischer-Tropsch waxes, and petroleum-based waxes, and modified products thereof.

  The release agent is dispersed in water together with ionic surfactants, polymer electrolytes such as polymer acids and polymer bases, and micronized with a homogenizer or pressure discharge type disperser that can be heated to a melting point or higher and subjected to strong shearing. A release agent dispersion liquid containing release agent particles having a particle diameter of 1 μm or less can be prepared.

  In the toner production method of the present invention, for example, stabilization during dispersion in the suspension polymerization method, and dispersion stability of the resin particle dispersion, colorant dispersion, and release agent dispersion in the emulsion polymerization aggregation method As the surfactant, a surfactant can be used.

  Examples of the surfactant include anionic surfactants such as sulfate, sulfonate, phosphate, and soap; cationic surfactants such as amine salt type and quaternary ammonium salt type; polyethylene glycol And nonionic surfactants such as polyphenols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, an ionic surfactant is preferable, and an anionic surfactant and a cationic surfactant are more preferable.

  In the toner of the present invention, in general, an anionic surfactant has a strong dispersion power and is excellent in dispersing resin particles and colorants. Therefore, an anionic surfactant is used as a surfactant for dispersing a release agent. It is advantageous to use a surfactant.

  The nonionic surfactant is preferably used in combination with the anionic surfactant or the cationic surfactant. The said surfactant may be used individually by 1 type, and may be used in combination of 2 or more type.

  Specific examples of anionic surfactants include fatty acid soaps such as potassium laurate, sodium oleate, and castor oil sodium; sulfates such as octyl sulfate, lauryl sulfate, lauryl ether sulfate, and nonyl phenyl ether sulfate; lauryl sulfonate , Sodium alkylnaphthalene sulfonate such as dodecylbenzene sulfonate, triisopropyl naphthalene sulfonate, dibutyl naphthalene sulfonate; sulfone such as naphthalene sulfonate formalin condensate, monooctyl sulfosuccinate, dioctyl sulfosuccinate, lauric acid amide sulfonate, oleic acid amide sulfonate Acid salts; lauryl phosphate, isopropyl phosphate, nonylphenyl ether Phosphoric acid esters such as Sufeto; dialkyl sulfosuccinate salts such as sodium dioctyl sulfosuccinate; sulfosuccinate salts such as sulfosuccinate lauryl disodium; and the like.

  Specific examples of the cationic surfactant include laurylamine hydrochloride, stearylamine hydrochloride, oleylamine acetate, stearylamine acetate, stearylaminopropylamine acetate, and other amine salts; lauryltrimethylammonium chloride, dilauryldimethylammonium Chloride, distearyldimethylammonium chloride, distearyldimethylammonium chloride, lauryldihydroxyethylmethylammonium chloride, oleylbispolyoxyethylenemethylammonium chloride, lauroylaminopropyldimethylethylammonium ethosulphate, lauroylaminopropyldimethylhydroxyethylammonium perchlorate, alkylbenzene Trimethylammonium chloride, Quaternary ammonium salts such as quilts trimethyl ammonium chloride; and the like.

  Specific examples of the nonionic surfactant include alkyl ethers such as polyoxyethylene octyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether; polyoxyethylene octyl phenyl ether, polyoxy Alkyl phenyl ethers such as ethylene nonyl phenyl ether; alkyl esters such as polyoxyethylene laurate, polyoxyethylene stearate, polyoxyethylene oleate; polyoxyethylene lauryl amino ether, polyoxyethylene stearyl amino ether, polyoxyethylene Alkylamines such as oleyl amino ether, polyoxyethylene soybean amino ether, polyoxyethylene beef tallow amino ether; Alkyl amides such as ethylene lauric acid amide, polyoxyethylene stearic acid amide, polyoxyethylene oleic acid amide; vegetable oil ethers such as polyoxyethylene castor oil ether and polyoxyethylene rapeseed oil ether; lauric acid diethanolamide, stearic acid Alkanolamides such as diethanolamide and oleic acid diethanolamide; sorbitan ester ethers such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate And so on.

  The content of the surfactant in each dispersion may be a level that does not inhibit the present invention, generally a small amount, specifically in the range of about 0.01 to 10% by weight, More preferably, it is the range of 0.05-5 weight%, More preferably, it is the range of about 0.1-2 weight%. If the content is less than 0.01% by weight, each dispersion such as a resin particle dispersion, a colorant dispersion, and a release agent dispersion becomes unstable. There are problems such as the release of specific particles due to the difference in stability between them, and when the amount exceeds 10% by weight, the particle size distribution of the particles becomes wide and the control of the particle size becomes difficult. It is not preferable for the reason. In general, a suspension polymerization toner dispersion having a large particle size is stable even if the amount of the surfactant used is small.

  Further, as the dispersion stabilizer used in the suspension polymerization method or the like, a slightly water-soluble and hydrophilic inorganic fine powder can be used. Examples of the inorganic fine powder that can be used include silica, alumina, titania, calcium carbonate, magnesium carbonate, tricalcium phosphate (hydroxyapatite), clay, diatomaceous earth, bentonite and the like. Among these, calcium carbonate, tricalcium phosphate, and the like are preferable from the viewpoints of easy particle size formation and easy removal.

  Also, a room temperature solid aqueous polymer or the like can be used. Specifically, cellulose compounds such as carboxymethyl cellulose and hydroxypropyl cellulose, polyvinyl alcohol, gelatin, starch, gum arabic and the like can be used.

  In addition, a charge control agent may be added to the toner of the present invention as necessary. Known charge control agents can be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used. When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination. The toner in the present invention may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

  The titanium compound used in the toner of the present invention is not particularly limited, and examples thereof include titanium oxide and metatitanic acid, barium titanate, magnesium titanate, calcium titanate, and strontium titanate.

  In particular, as the small particle size titanium compound A, it is preferable to use titanium oxide having a primary particle size of 7 to 40 nm in terms of volume average particle size, which has good chargeability, charge uniformity within the toner particles, and a charging environment. It is more preferable from the viewpoints of obtaining stability and not affecting the fluidity of the toner and developer and the transparency of the toner after fixing.

  The large particle size titanium compound A has a volume average from the viewpoint of charge control, in particular, charge exchangeability between toner particles and toner particles, between toner particles and carriers, and reduction in surface state change due to developer agitation and mixing. It is desirable to use a titanium compound selected from titanium oxide and metatitanic acid having a particle size of 20 to 300 nm.

  There is a relationship DA ≦ DB between the volume average particle diameters of the titanium compound A and the titanium compound B (DA and DB, respectively), and a preferable range thereof is DB-DA ≧ 50 nm, more preferably DB-DA ≧ 100 nm, more preferably DB-DA ≧ 200 nm. As described later, the effect of the volume resistivity of the titanium compound can be further clarified by the difference in volume average particle diameter.

A relationship of RA ≦ RB and RA ≦ 12.0 is required between the powder resistivity of the titanium compound A and the titanium compound B (RA and RB, respectively), and a preferable range thereof is RB−RA ≧ 0. .5, more preferably RB-RA ≧ 1.0, and even more preferably RB-RA ≧ 2.0.

Due to the RA ≦ 12.0 of the small particle size titanium compound A, the uneven distribution of the charge amount on the surface of the toner particles is reduced, and the toner particles by RB due to the high volume resistivity ( powder resistivity) of the large particle size titanium compound B. -The charge exchange property between the toner particles and between the toner particles and the carrier can be improved. In the case of RA> RB, the charge on the surface of the toner particles moves to other toner particles, carriers, etc. before becoming uniform on the surface, so the charge amount does not increase, and the developer is likely to be fogged during development. The problem of becoming may occur.

  It is preferable that the relationship of 0.15 ≦ (WA / WB) ≦ 3.0 is satisfied between the contents of the small particle size titanium compound A and the large particle size titanium compound B (WA and WB, respectively).

The toner of the present invention, adhesion to the toner particles of the titanium compound to externally added meet the C from the following conditions A.
[Condition A] Ratio of titanium compound falling off from toner particles when ultrasonic vibration (output 20 W, frequency: 20 kHz) is applied for 1 minute ≦ 7 wt%
[Condition B] Ratio of titanium compound falling off when ultrasonic vibration (output 60 W, frequency: 20 kHz) is applied for 30 minutes ≦ 40 wt%
[Condition B] Ratio of titanium compound remaining on toner particles due to desorption under the above two conditions ≧ 50% by weight

Specifically, the adhesion force is to satisfy the following conditions a to c. Note that WA represents the content (wt%) of the titanium compound A, and WB represents the content (wt%) of the titanium compound B.
[Condition a] Formula: Pa ≦ 7
[Condition b] Formula: Pb ≦ 40
[Condition c] Formula: Pc ≧ 50
[Where a is the amount of titanium compound released from toner particles when ultrasonic vibration (output 20 W, frequency: 20 kHz) is applied in the toner dispersion for 1 minute, and b is ultrasonic vibration (output 60 W in the toner dispersion). , Frequency: 20 kHz) amount of titanium compound desorbed from toner particles when given for 30 minutes, c represents the amount of fine particles remaining on the toner particles after desorption, and Pa = 100 × a / ( WA + WB), Pb = 100 × b / (WA + WB), and Pc = 100 × c / (WA + WB). ]

  In general, toner is subjected to stress such as stirring, rubbing, and pressing during development and transfer, and the external additive is attached to or detached from the surface of the toner particles, and the adhesion state of the external additive to the toner changes. By controlling such embedding and detachment, good transferability can be maintained.

  In the toner of the present invention, other external additives can be added to such an extent that charging and charge exchange are not affected. As specific examples of other external additives, inorganic metal oxides such as aluminum oxide, magnesium oxide, zinc oxide, chromium oxide, antimony trioxide, zirconium oxide, calcium carbonate, and calcium phosphate are preferably used. Particles having an abrasive effect such as cerium and manganese dioxide can also be added.

  The addition amount of the external additive fine particles is preferably in the range of 0.1 to 1.0 part by weight with respect to 100 parts by weight of the toner particles. Further, the addition amount of the large-sized metal oxide fine particles is preferably 0.5 to 2.0 parts by weight with respect to 100 parts by weight of the toner particles.

  The external additive fine particles can be surface-treated. More specifically, the dispersion of the external additive on the toner surface is performed by performing a hydrophobic treatment with dimethyldimethoxysilane, hexamethyldisilazane (HMDS), methyltrimethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, or the like. As described above, the effect of improving the charging property, the charge exchange property, and the powder fluidity is increased.

  Further, an organic material may be added to the toner of the present invention for the purpose of maintaining and improving cleaning properties, reducing photoreceptor wear, and the like, and solid lubricants such as higher alcohol fine particles, fatty acids, aliphatic alcohols, fatty acid metal salts, etc. Can also be used.

  The toner of the present invention can be produced by mixing toner particles and metal oxide fine particles as an external additive with a Henschel mixer or a V blender. In addition, when the toner particles are produced by a wet method, external addition can be performed by a wet method.

(Developer for developing electrostatic image)
The developer for developing an electrostatic image of the present invention contains the toner for developing an electrostatic image of the present invention described above. That is, the developer for developing an electrostatic image of the present invention (hereinafter sometimes simply referred to as “developer”) is produced by mixing the toner described above and the following carrier.

  The absolute value of the charge amount of the toner and carrier is preferably 30 to 60 μC / g.

  The mixing ratio (weight ratio) between the toner and the carrier in the developer of the present invention is preferably in the range of toner: carrier = 1: 99 to 20:80, preferably in the range of 3:97 to 12:88. It is more preferable.

  There is no restriction | limiting in particular as a carrier which can be used for the developing agent of this invention, A well-known carrier can be used. For example, a resin-coated carrier having a resin coating layer on the surface of the core material can be exemplified. Further, it may be a resin dispersion type carrier in which magnetic powder or the like is dispersed in a matrix resin.

  Coating resins and matrix resins used for carriers include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic. Examples include acid copolymers, straight silicone resins composed of organosiloxane bonds or modified products thereof, fluororesins, polyesters, polycarbonates, phenol resins, epoxy resins, urea resins, urethane resins, melamine resins, etc. It is not limited.

  In general, the carrier preferably has an appropriate electric resistance value, and it is preferable to disperse the conductive fine powder in the resin for adjusting the resistance. Examples of the conductive fine powder include metals such as gold, silver and copper, carbon black, titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, tin oxide, and carbon black. However, it is not limited to these.

  Examples of the carrier core material include magnetic metals such as iron, nickel, and cobalt, magnetic oxides such as ferrite and magnetite, and glass beads. However, in order to use the carrier for the magnetic brush method, a magnetic material is used. Preferably there is. The volume average particle size of the carrier core material is preferably in the range of 10 to 100 μm, and more preferably in the range of 25 to 50 μm.

  In order to coat the surface of the core material of the carrier with a resin, a method of coating the coating resin and, if necessary, various additives with a solution for forming a coating layer dissolved in an appropriate solvent is employed. The solvent is not particularly limited and may be appropriately selected in consideration of the coating resin to be used, coating suitability, and the like.

  Specific resin coating methods include a dipping method in which the powder of the carrier core material is immersed in the coating layer forming solution, a spray method in which the coating layer forming solution is sprayed on the surface of the carrier core material, and a carrier core material. Examples thereof include a fluidized bed method in which a coating layer forming solution is sprayed in a state of being suspended by flowing air, and a kneader coater method in which a carrier core material and a coating layer forming solution are mixed in a kneader coater to remove the solvent.

(Image forming method)
The image forming method of the present invention will be described in detail below.
The image forming method of the present invention uses at least a latent image forming step for forming an electrostatic latent image on the surface of the latent image carrier and a developer containing at least a toner, and the electrostatic latent image formed on the surface of the latent image carrier. A developing process for developing the image to form a toner developed image, a process for transferring the toner image formed on the surface of the latent image carrier onto the recording medium, and the toner image transferred on the surface of the recording medium are thermally fixed. And a fixing step, wherein the toner for developing an electrostatic charge image of the present invention is used as the toner. The same effect can be obtained by using the toner alone as a developer, or by using the developer for developing an electrostatic image of the present invention composed of toner and carrier.

  The latent image forming step is a step of forming an electrostatic latent image by uniformly charging the surface of the latent image carrier with a charging means and then exposing the latent image carrier with a laser optical system or an LED array. It is. Examples of the charging means include a non-contact charger such as corotron and scorotron, and a contact method in which a latent image carrier surface is charged by applying a voltage to a conductive member in contact with the latent image carrier surface. Any type of charger may be used. However, a contact charging type charger is preferable from the viewpoint that the amount of ozone generated is small and the effect of excellent printing durability is exhibited. In the contact charging type charger, the shape of the conductive member may be any of a brush shape, a blade shape, a pin electrode shape, a roller shape, and the like, but a roller-like member is preferable. The image forming method of the present invention is not subject to any particular limitation in the latent image forming process.

  The developing step is a step of bringing a developer carrying member having a developer layer containing at least toner on the surface thereof into contact with or approaching the surface of the latent image carrying member to the electrostatic latent image on the surface of the latent image carrying member. In which a toner image (developed image) is formed on the surface of the latent image carrier. The development method can be performed using a known method, but examples of the development method using a two-component developer include a cascade method and a magnetic brush method. The image forming method of the present invention is not particularly limited with respect to the developing method.

  The transfer step is a step of transferring a toner image formed on the surface of the latent image carrier to form a transfer image. Examples of a transfer device for transferring a toner image from a latent image carrier onto paper or the like include conventional corotron and scorotron transfer, but a method using a conductive bias transfer roll made of an elastic material with less generation of ozone or the like Is mentioned. As a transfer roll, a metal roll whose surface is covered with a rubber layer and this surface rubber layer is fluorine treated is often used. Further, in order to effectively avoid the situation where residual toner or the like adheres to this type of transfer roll, a cleaning device is provided in which a cleaning blade is placed in contact with the transfer roll. Here, as the cleaning blade, for example, an elastic body such as urethane rubber is used so as not to damage the fluorine-treated film that is the surface coating layer of the transfer roll. However, the transfer blade member and the roll cleaning means are particularly limited. It is not a thing. At the time of transfer, the bias transfer roll is brought into pressure contact with the latent image carrier at a pressure of 5 g / cm or more to perform contact transfer for transferring a toner image onto a sheet.

  In particular, the transfer step may be a step of performing direct transfer using a bias roll. Thus, an image forming method can be obtained in which transfer efficiency due to aggregation between toner particles is not reduced even when direct transfer is performed.

  The fixing step is a step of fixing the toner image transferred on the surface of the recording medium with a fixing device. As the fixing device, a heat fixing device using a heat roll is preferably used. The heat fixing device includes a fixing roller having a heater lamp for heating inside a cylindrical metal core, a so-called release layer formed on the outer peripheral surface by a heat resistant resin film layer or a heat resistant rubber film layer, and the fixing roller. The pressure roller or pressure belt is disposed in pressure contact with the roller and has a heat-resistant elastic body layer formed on the outer peripheral surface of the cylindrical metal core or the surface of the belt-like base material. The fixing process of an unfixed toner image is performed by inserting a recording medium on which an unfixed toner image is formed between a fixing roller and a pressure roller or a pressure belt to heat the binder resin, additive, etc. in the toner. Fix by melting. In the image forming method of the present invention, the fixing method is not particularly limited.

  In the image forming method of the present invention, when producing a full-color image, each of the plurality of latent image carriers has a developer carrier of each color, and the plurality of latent image carriers and developer carriers. Through a series of processes consisting of a latent image forming process, a developing process, and a transfer process, each color toner image is sequentially stacked on the same recording medium surface, and the stacked full-color toner images are fixed. An image forming method in which heat fixing is performed in the process is preferably used. By using the developer for developing an electrostatic image in the image forming method, stable development, transfer, and fixing performance can be obtained even in a tandem system suitable for, for example, miniaturization and color acceleration. .

  Examples of the recording medium to which the toner image is transferred include plain paper, OHP sheet, and the like used for electrophotographic copying machines and printers. In order to further improve the smoothness of the image surface after fixing, the surface of the recording medium is preferably as smooth as possible. For example, coated paper in which the surface of plain paper is coated with a resin, art paper for printing, etc. Can be preferably used.

  According to the image forming method of the present invention, it is possible to obtain a high-quality image with high transfer efficiency without causing image quality defects such as image unevenness over a long period of time.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the following description, “parts” means “parts by weight” unless otherwise specified.

(Measuring method of particle size and particle size distribution)
The particle size and particle size distribution measurement will be described. When the particles to be measured were 2 μm or more, a Coulter counter TA-II type (manufactured by Beckman Coulter, Inc.) was used as the measuring apparatus, and an ISOTON-II (manufactured by Beckman Coulter, Inc.) was used as the electrolyte.

  As a measuring method, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant. This was added to 100 to 150 ml of the electrolytic solution.

  The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute, and the particle size distribution of particles of 2 to 60 μm is measured using the Coulter counter TA-II with an aperture diameter of 100 μm. Volume average distribution and number average distribution were determined. The number of particles to be measured was 50,000.

  The particle size distribution of the toner (toner particles) was determined by the following method. For the particle size range (channel) obtained by dividing the measured particle size distribution, a volume cumulative distribution is drawn from the smaller particle size, and the volume average particle size of 16% is defined as D16, and the volume average of 50% is accumulated. The particle size is defined as D50. Furthermore, the volume average particle diameter that is 84% cumulative is defined as D84.

Here, the volume average particle diameter is D50, and GSD was calculated by the following equation.
Formula: GSD = {(D50 / D16) + (D84 / D50)} / 2

  When the particle to be measured was less than 2 μm, the particle size was measured using a laser diffraction particle size distribution analyzer (LA-700: manufactured by Horiba, Ltd.). As a measurement method, a sample in a dispersion is adjusted to have a solid content of about 2 g, and ion exchange water is added thereto to make about 40 ml. This is put into the cell until an appropriate concentration is reached, waits for about 2 minutes, and is measured when the concentration in the cell becomes almost stable. The obtained volume average particle diameter for each channel was accumulated from the smaller volume average particle diameter, and the volume average particle diameter was determined to be 50%.

  When measuring powders such as external additives, 2 g of a measurement sample is added to 50 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate, and dispersed for 2 minutes with an ultrasonic disperser (1000 Hz). Then, a sample was prepared and measured by the same method as the above-mentioned dispersion.

(Toner shape factor SF1 measurement method)
The toner shape factor SF1 is calculated by taking the optical microscope image of the toner spread on the slide glass into a Luzex image analyzer through a video camera and calculating the square of the maximum length of 50 toners / projection area (ML ² / A). , Obtained by calculating an average value.

(Measurement method of molecular weight and molecular weight distribution of toner and resin particles)
In the electrostatic charge developing toner of the present invention, the specific molecular weight distribution is obtained under the following conditions. GPC uses “HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation)”, and the column uses two “TSKgel, SuperHM-H (6.0 mm ID × 15 cm, manufactured by Tosoh Corporation)” THF (tetrahydrofuran) was used as an eluent. As experimental conditions, the sample concentration was 0.5%, and the flow rate was 0.6 ml / min. The experiment was conducted using a sample injection amount of 10 μl, a measurement temperature of 40 ° C., and an IR detector. The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A-2500”. ”,“ F-4 ”,“ F-40 ”,“ F-128 ”, and“ F-700 ”.

(Measuring method of melting point of release agent and glass transition temperature of toner)
The melting point of the release agent used in the toner of the present invention and the glass transition temperature of the toner were determined from the main maximum peak measured according to ASTM D3418-8.

  DSC-7 manufactured by Perkin Elmer Co. can be used for measurement of the main maximum peak. The temperature correction of the detection part of this apparatus uses the melting point of indium and zinc, and the correction of heat quantity uses the heat of fusion of indium. As the sample, an aluminum pan was used, an empty pan was set as a control, and the measurement was performed at a heating rate of 10 ° C./min.

(Toner charge amount)
The amount of charge was determined by leaving both the toner assemblage and the carrier in an atmosphere of 25 ° C. and 55% RH for 24 hours, and placing TC (TC (wt%) = toner weight / (toner weight +) in a glass bottle with a lid. The toner composition and the carrier were collected so that the carrier weight) × 100) was 5 wt%, and the tumbler stirring was performed for 60 minutes in each atmosphere, and the stirred developer was subjected to conditions of 25 ° C. and 55% RH. Measured with TB200 manufactured by Toshiba.

  The charge amount in the actual machine evaluation test was obtained by collecting about 0.3 to 0.7 g of the developer on the surface of the mag sleeve (developer carrier) in the developing machine, and at 25 ° C. and 55% RH as described above. And measured with a TB200 manufactured by Toshiba Corporation.

(External additive (metal oxide fine particles) powder resistivity)
As shown in FIG. 1, the measurement sample 3 is sandwiched between the lower electrode 4 and the upper electrode 2 with a thickness of 0.8 mm, the thickness is measured with a dial gauge while pressing from above, and the electrical resistance of the measurement sample 3 is set to a high voltage resistance. A total of 5 was measured.

Specifically, the external additive sample was filled in the lower electrode 4 of 100φ (diameter 100 mm), the upper electrode 2 was set, a load of 3.43 kg was applied from above, and the thickness was measured with a dial gauge. Next, a voltage of 1.0 ^3.8 (V / cm) was applied and the current value was read to determine the powder resistivity.

(External additive adhesion strength)
The adhesion strength of the external additive was measured as follows. 2 g of toner particles are added to 40 ml of 0.2% surface-active aqueous solution and sufficiently dispersed so that the toner particles are immersed in the aqueous solution. In this state, ultrasonic vibration having a frequency of 20 kHz is applied at a predetermined output for a predetermined time, and the external additive detached from the toner particles is measured.

The ratio between the amount of the external additive desorbed under the following conditions and the amount of the external additive adhering before application of ultrasonic vibration was calculated. In the table, “strong” in the adhesion strength corresponds to the condition (C), “medium” corresponds to the condition (B), and “weak” corresponds to the condition (A).
Condition (A): Amount of external additive desorbed from toner particles when ultrasonic vibration (output 20 W, frequency: 20 kHz) is applied for 1 minute (B) Ultrasonic vibration (output 60 W, frequency: 20 kHz) for 30 minutes Amount of external additive that desorbs from toner particles when applied (C): Amount of external additive remaining on toner particles after desorption under stress of conditions (A) and (B)

(Image density)
The image density was measured using an image densitometer (X-Rite 404A: manufactured by X-Rite).

(Carrier volume resistivity)
A sample of the carrier was filled on the lower electrode of the cell (100 mmφ, thickness 1.0 mm), the upper electrode was set, a load of 3.43 kg was applied from above, and the thickness was measured with a dial gauge. Next, voltage was applied and the current value was read to determine the volume resistivity (see FIG. 1).

(Manufacture of toner particles)
The toner in the examples was obtained by the following method.
In the aggregation coalescence method, the following resin fine particles, colorant particle dispersion, and release agent particle dispersion were prepared. Next, while mixing and stirring a predetermined amount of these, an inorganic metal salt polymer is added thereto and ionically neutralized to form aggregates of the above particles, and resin fine particles are added before reaching the desired toner particle size Then, the toner particle diameter is obtained. After the pH of the system is adjusted from a weakly acidic to a neutral range with an inorganic hydroxide, it is heated to a temperature higher than the glass transition temperature of the resin fine particles so as to fuse together. After completion of the reaction, a desired toner is obtained through sufficient washing, solid-liquid separation, and drying processes.

-Adjustment of resin fine particle dispersion-
-Styrene: 370 parts-n-butyl acrylate: 30 parts-Acrylic acid: 8 parts-Carbon tetrabromide: 4 parts-Dodecanethiol: 24 parts

  6 parts of a nonionic surfactant (Nonipol 400: manufactured by Sanyo Kasei Co., Ltd.) and 10 parts of an anionic surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) are mixed into 550 parts of ion-exchanged water. The dissolved one was dispersed and emulsified in a flask, and 50 parts of ion-exchanged water in which 4 g of ammonium persulfate was dissolved was added while slowly stirring and mixing for 10 minutes.

  Next, after sufficiently replacing the nitrogen in the system sufficiently, the flask was stirred and heated in an oil bath with an oil bath until the temperature reached 70 ° C., and emulsion polymerization was continued for 5 hours. Thus, an anionic resin fine particle dispersion having a center diameter of 152 nm, a solid content of 40%, a glass transition temperature of 58 ° C., and a weight average molecular weight (hereinafter sometimes abbreviated as Mw) 11700 was obtained.

-Preparation of colorant dispersion (1)-
・ Carbon black (Mogal L: manufactured by Cabot): 60 parts ・ Nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.): 6 parts ・ Ion-exchanged water: 240 parts

  A solution obtained by mixing and dissolving the above is stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then dispersed with an optimizer to give a colorant having a volume average particle diameter of 250 nm ( A colorant dispersant (1) having carbon black particles dispersed therein was prepared.

-Preparation of colorant dispersion (2)-
Cyan pigment (B15: 3): 60 parts Nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.): 5 parts Ion exchange water: 240 parts

  A solution obtained by mixing and dissolving the above is stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then dispersed with an optimizer to give a colorant having a volume average particle diameter of 250 nm ( Cyan pigment) A colorant dispersant (2) in which particles were dispersed was prepared.

-Adjustment of release agent dispersion-
Paraffin wax (HNP0190: Nippon Seiwa Co., Ltd., melting point 85 ° C.): 100 parts Cationic surfactant (Sanisol B50: Kao Corporation): 5 parts Ion exchange water: 240 parts

  The above was mixed, heated to 95 ° C., dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA) for 10 minutes, and then dispersed with a pressure discharge type homogenizer. A release agent dispersion liquid in which release agent particles having an average particle diameter of 550 nm were dispersed was prepared.

-Preparation of toner particles (1)-
-Resin fine particle dispersion: 234 parts-Colorant dispersion (1): 30 parts-Release agent dispersion: 40 parts-Polyaluminum chloride: 1.9 parts-Ion exchange water: 600 parts

  The above was thoroughly mixed and dispersed in a round stainless steel flask using Ultra Turrax T50 (manufactured by IKA). The flask was heated to 55 ° C. at 1 ° C./min with stirring in a heating oil bath. After holding at 55 ° C. for 40 minutes, it was confirmed that aggregated particles having a volume average particle diameter D50 of 5.0 μm were produced.

  Further, when the temperature of the heating oil bath was raised and maintained at 56 ° C. for 2 hours, the volume average particle diameter D50 of the aggregated particles was 6.1 μm. Thereafter, 34 parts of the resin fine particle dispersion was added to the dispersion containing the aggregated particles, and then the temperature of the heating oil bath was set to 50 ° C. and held for 30 minutes. After adjusting the pH of the system to 7.0 by adding a 1N sodium hydroxide solution to the dispersion containing the aggregated particles, the stainless steel flask is sealed, and stirring is continued using a magnetic seal up to 88 ° C. Heated and held for 4 hours.

  After cooling, the reaction product was filtered off, washed four times with ion exchange water, and then freeze-dried to produce toner particles (1). The volume average particle diameter D50 of the toner particles (1) is 6.5 μm, and the average value of the shape factor SF1 is 133.

-Preparation of toner particles (2)-
A material having the same composition as the toner particles (1) is thoroughly mixed and dispersed in a round stainless steel flask with Ultra Turrax T50 (manufactured by IKA), and then stirred at 1 ° C./min while stirring the flask in an oil bath for heating. To 55 ° C. After holding at 55 ° C. for 25 minutes, it was confirmed that aggregated particles having a volume average particle diameter D50 of 3.0 μm were produced.

When the temperature of the heating oil bath was further raised and held at 56 ° C. for 1.5 hours, the volume average particle diameter D50 of the aggregated particles was 4.2 μm. Thereafter, 30 parts of the resin fine particle dispersion was added to the dispersion containing the aggregated particles, and then the temperature of the heating oil bath was set to 50 ° C. and held for 30 minutes. After adjusting the pH of the system to 7.0 by adding a 1N sodium hydroxide solution to the dispersion containing the aggregated particles, the stainless steel flask is sealed, and stirring is continued using a magnetic seal up to 88 ° C. Heated and held for 4 hours.
After cooling, the reaction product was filtered off, washed four times with ion exchange water, and then freeze-dried to produce toner particles (2). The volume average particle diameter D50 of the toner particles (2) is 4.8 μm, and the average value of the shape factor SF1 is 123.

-Preparation of toner particles (3)-
A material having the same composition as the toner particles (1) is thoroughly mixed and dispersed in a round stainless steel flask with Ultra Turrax T50 (manufactured by IKA), and then stirred at 1 ° C./min while stirring the flask in an oil bath for heating. To 55 ° C. After holding at 55 ° C. for 40 minutes, it was confirmed that aggregated particles having a volume average particle diameter D50 of 5.0 μm were produced.

  Further, when the temperature of the heating oil bath was raised and held at 56 ° C. for 3 hours, the volume average particle diameter D50 of the aggregated particles was 6.9 μm. Thereafter, 47 parts of the resin fine particle dispersion was added to the dispersion containing the aggregated particles, and then the temperature of the heating oil bath was set to 50 ° C. and held for 30 minutes. After adjusting the pH of the system to 7.0 by adding a 1N sodium hydroxide solution to the dispersion containing the aggregated particles, the stainless steel flask is sealed, and stirring is continued using a magnetic seal up to 88 ° C. Heated and held for 4 hours.

  After cooling, the reaction product was filtered off, washed four times with ion exchange water, and then freeze-dried to produce toner particles (3). The volume average particle diameter D50 of the toner particles (3) is 7.5 μm, and the average value of the shape factor SF1 is 140.

-Preparation of toner particles (4)-
A material having the same composition as the toner particles (1) is thoroughly mixed and dispersed in a round stainless steel flask with Ultra Turrax T50 (manufactured by IKA), and then stirred at 1 ° C./min while stirring the flask in an oil bath for heating. To 55 ° C. After holding at 55 ° C. for 40 minutes, it was confirmed that aggregated particles having a volume average particle diameter D50 of 5.0 μm were produced.

  Further, when the temperature of the heating oil bath was raised and maintained at 56 ° C. for 4 hours, the volume average particle diameter D50 of the aggregated particles was 8.0 μm. Thereafter, 60 parts of the resin fine particle dispersion was added to the dispersion containing the aggregated particles, and then the temperature of the heating oil bath was set to 50 ° C. and held for 30 minutes. After adjusting the pH of the system to 7.0 by adding a 1N sodium hydroxide solution to the dispersion containing the aggregated particles, the stainless steel flask is sealed, and the stirring is continued to 83 ° C. using a magnetic seal. Heated and held for 4 hours.

  After cooling, the reaction product was filtered off, washed four times with ion exchange water, and then freeze-dried to produce toner particles (4). The volume average particle diameter D50 of the toner particles (4) is 9.6 μm, and the average value of the shape factor SF1 is 143.

-Preparation of toner particles (5)-
Toner particles (5) were produced in the same manner as the toner particles (1) except that the colored particle dispersion (2) was used instead of the colored particle dispersion (1). The volume average particle diameter D50 of the toner particles (5) is 6.6 μm, and the average value of the shape factor SF1 is 132.

(Carrier production)
17 parts of toluene, 3 parts of a styrene-methacrylate copolymer (component ratio: 40/60), and 0.2 part of carbon black (R330: manufactured by Cabot) were mixed and stirred with a stirrer for 10 minutes. A dispersed coating layer forming solution was prepared. Next, this coating solution and 100 parts of ferrite particles (volume average particle size: 45 μm) are put into a vacuum degassing type kneader and stirred at 60 ° C. for 30 minutes, and then degassed by further reducing pressure while heating. The carrier was prepared by drying. This carrier had a volume resistivity of 1014 Ωcm when an electric field of 1000 V / cm was applied.

(Preparation of developer 1 for developing an electrostatic image)
Toner particles (1): 100 parts Anatase-type titanium oxide (volume average particle diameter: 130 nm): 0.3 part Metametatate compound (volume average particle diameter: 30 nm): 0.8 part

  The above components were blended for 15 minutes at a peripheral speed of 30 m / s using a 5-liter Henschel mixer, and then coarse particles were removed using a sieve having an opening of 45 μm to prepare a toner. Further, 100 parts of the carrier and 6 parts of the toner were stirred for 20 minutes at 40 rpm with a V-blender, and sieved with a sieve having an opening of 212 μm to produce developer 1 for developing an electrostatic image. .

(Preparation of developer 2 for developing an electrostatic image)
Toner particles (1): 100 parts Anatase-type titanium oxide (volume average particle diameter: 130 nm): 0.25 parts Metamethanic acid compound (volume average particle diameter: 30 nm): 0.7 parts

・
A developer 2 for developing an electrostatic image was prepared in the same manner as the developer 1 for developing an electrostatic image except that the constitution was as described above.

(Preparation of developer 3 for developing an electrostatic image)
Toner particles (2): 100 parts Anatase-type titanium oxide (volume average particle diameter: 130 nm): 0.3 parts Metametatinate compound (volume average particle diameter: 30 nm): 0.7 parts

  A developer 3 for developing an electrostatic image was prepared in the same manner as the developer 1 for developing an electrostatic image except that the constitution was the above-described components.

(Preparation of developer 4 for developing an electrostatic image)
Toner particles (3): 100 parts Anatase-type titanium oxide (volume average particle size: 130 nm): 0.5 parts Metamethanic acid compound (volume average particle size: 30 nm) 1.0 part

  A developer 4 for developing an electrostatic charge image was produced in the same manner as the developer 1 for developing an electrostatic charge image except that the constitution was changed to the above components.

(Preparation of developer 5 for developing electrostatic image)
Toner particles (1): 100 parts Anatase-type titanium oxide (volume average particle diameter: 130 nm): 0.5 parts Metamethanic acid compound (volume average particle diameter: 30 nm): 1.1 parts

  A developer 5 for developing an electrostatic charge image was produced in the same manner as the developer 1 for developing an electrostatic charge image except that the constitution was changed to the above components.

(Preparation of developer 6 for developing an electrostatic image)
Toner particles (5): 100 parts Anatase-type titanium oxide (volume average particle diameter: 130 nm): 0.4 parts Metametatitanic acid compound (volume average particle diameter: 30 nm): 0.9 parts

  A developer 6 for developing an electrostatic charge image was produced in the same manner as the developer 1 for developing an electrostatic charge image except that the constitution was as described above.

(Preparation of developer 7 for developing an electrostatic image)
Toner particles (1): 100 parts Silica fine particles (volume average particle diameter: 12 nm): 1.9 parts

  A developer 7 for developing an electrostatic charge image was produced in the same manner as the developer 1 for developing an electrostatic charge image except that the constitution was changed to the above components.

(Preparation of developer 8 for developing an electrostatic image)
Toner particles (2): 100 parts Silica fine particles (volume average particle diameter: 12 nm): 0.5 parts Silica fine particles (volume average particle diameter: 40 nm): 1.1 parts

  A developer 8 for developing an electrostatic charge image was produced in the same manner as the developer 1 for developing an electrostatic charge image except that the constitution was as described above.

(Preparation of developer 9 for developing electrostatic image)
Toner particles (1): 100 parts. Anatase type titanium oxide (volume average particle size: 130 nm) 0.5 part. Rutile type titanium oxide (volume average particle size: 15 nm): 1.8 parts.

  A developer 9 for developing an electrostatic charge image was produced in the same manner as the developer 1 for developing an electrostatic charge image except that the configuration was changed to the above components.

(Preparation of developer 10 for developing an electrostatic image)
Toner particles (4): 100 parts Anatase type titanium oxide (volume average particle diameter: 130 nm): 0.5 part Rutile type titanium oxide (volume average particle diameter: 15 nm): 0.8 part

  A developer 10 for developing an electrostatic charge image was produced in the same manner as the developer 1 for developing an electrostatic charge image except that the constitution was as described above.

  The characteristic values of the produced electrostatic charge image developing developers 1 to 10 are shown in Table 1.

Example 1
The developability and transferability of the developer 1 for developing an electrostatic charge image were evaluated using a modified Docu print C2221 (manufactured by Fuji Xerox Co., Ltd.). The evaluation contents and criteria are shown below, and the evaluation results are shown in Table 2. This machine has a bias transfer roll in the transfer device. The evaluation contents and criteria are shown below, and the evaluation results are shown in Table 2.

(Evaluation of initial developability and transferability)
A solid patch of 5cm x 2cm is developed in a single color mode in an environment of high temperature and high humidity (30 ° C, 80% RH), and the developed toner image on the surface of the photoreceptor is transferred using the adhesiveness of the tape surface. The weight (W1) was measured. Next, the same developed toner image was transferred onto the surface of paper (J paper: manufactured by Fuji Xerox Office Supply), and the weight (W2) of the transferred image was measured. From these, the transfer efficiency was determined by the following formula and the transferability was evaluated. The developability was evaluated based on the weight of W1 at this time.
Formula: Transfer efficiency (%) = (W2 / W1) × 100

[Development evaluation criteria]
-: W1 is 4.5 g / m2 or more-: W1 is 4.0 or more and less than 4.5 g / m2-: W1 is less than 4.0 g / m2

[Evaluation criteria for transferability (transfer efficiency)]
・ ○: Transfer efficiency is 90% or more ・ △: Transfer efficiency is 85% or more and less than 90% ・ ×: Transfer efficiency is less than 85%

[Evaluation criteria for uneven transfer]
・ ○: There is no visual unevenness in the halftone image. Δ: There is a visual unevenness in the halftone image, but there is no problem in practical use. ×: There are many unevennesses visible in the halftone image.

(Evaluation of maintainability)
After 50,000 sheets were continuously printed after the initial evaluation, the transfer efficiency was determined in the same manner as described above. Thereafter, the rate of decrease from the initial transfer efficiency was determined by the following formula, and judgment was made according to the following criteria.
Formula: Transfer efficiency maintainability (%) = (Transfer efficiency after printing) / (Initial transfer efficiency) × 100

[Evaluation criteria for transfer efficiency maintenance]
・ ○: Transfer efficiency is 90% or more ・ △: Transfer efficiency is 85% or more and less than 90% ・ ×: Transfer efficiency is less than 85%

[Evaluation criteria for photoconductor damage]
After confirming the transfer efficiency, the surface of the photoreceptor in the evaluation machine was visually observed.
・ ○: Level where no major damage is observed and no problem ・ △: Deterioration is observed from the initial state, but no problem in actual use ・ ×: Level that affects the copy image

(Example 2)
The developer 2 for developing an electrostatic image was evaluated using a modified A-color 935 (Fuji Xerox Co., Ltd.). The evaluation results are shown in Table 2. The transfer device of this machine is based on the corotron method.

(Examples 3 to 6)
Evaluation of developers 3 to 6 for developing electrostatic images was performed using a modified Docu print C2221 (manufactured by Fuji Xerox Co., Ltd.). The evaluation results are shown in Table 2.

(Comparative Examples 1-4)
The developers 7 to 10 for developing electrostatic images were evaluated using a modified Docu print C2221 (Fuji Xerox Co., Ltd.). The evaluation results are shown in Table 2.

  From the results of Table 2, it is a toner obtained by externally adding two kinds of titanium compounds, and even when a small particle size toner (specifically, for example, 4 μm to 8 μm) is used, the development characteristics are not deteriorated. It can be seen that it is possible to provide an image forming method capable of maintaining transferability for a long period of time, a toner for developing electrostatic charge, a method for producing the same, and a developer.

  In addition, toners with external addition of two types of titanium compounds and specified volume average particle size and charge amount within a specific range are used in systems having a bias roll transfer system, such as initial development performance, transfer efficiency, transfer unevenness, etc. It can also be seen that it has excellent characteristics and transfer efficiency maintenance.

It is the schematic for demonstrating the method to measure a powder resistivity.

Explanation of symbols

101 guard electrode 102 upper electrode 103 measurement sample 104 lower electrode 105 sample holding ring 106 electrometer

Claims (3)

In an electrostatic latent image developing toner containing at least toner particles and an external additive excluding silica ,
The external additive is two kinds of additives including titanium compound A and titanium compound B,
The toner particles have a volume average particle size of 4 μm to 8 μm, a GSD showing a volume particle size distribution of 1.23 or less, and a shape factor SF1 of 110 to 140 .
The electrostatic latent image developing toner, wherein the titanium compound A and the titanium compound B satisfy the following conditions.
Condition (1): RA <RB
Condition (2): DA <DB
Condition (3): RA ≦ 12.0
(Where RA and RB are the powder resistivity LogE (Ω · cm) when the applied voltage of the titanium compound A and the titanium compound B is 1.0 ^3.8 (V / cm), DA and DB are the titanium compound A and The volume average particle diameter (nm) of the titanium compound B is shown.)
Condition a: Pa ≦ 7
Condition b: Pb ≦ 40
Condition c: Pc ≧ 50
(Wa is the content (wt%) of titanium compound A, WB is the content (wt%) of titanium compound B, and a is the ultrasonic vibration (output 20 W, frequency: 20 kHz) in the toner dispersion. The amount of titanium compound desorbed from the toner particles when given for a minute, b is the amount of titanium compound desorbed from the toner particles when ultrasonic vibration (output 60 W, frequency: 20 kHz) is given for 30 minutes in the toner dispersion, and c is a and b indicate the amount of fine particles remaining on the toner particles after desorption, and Pa = 100 × a / (WA + WB), Pb = 100 × b / (WA + WB), and Pc = 100 × c / (WA + WB). is there.) A latent image forming step for forming an electrostatic latent image on at least the surface of the latent image carrier, and a developer containing at least a toner, and developing the electrostatic latent image formed on the surface of the latent image carrier to develop a toner developed image An image forming process including: a developing process for forming a toner image; a process for transferring a toner image formed on the surface of the latent image carrier onto a recording medium; and a fixing process for thermally fixing the toner image transferred on the surface of the recording medium. In the method
The toner includes at least toner particles and an external additive excluding silica ,
The toner particles have a volume average particle size of 4 μm to 8 μm, a GSD showing a volume particle size distribution of 1.23 or less, and a shape factor SF1 of 110 to 140,
The image forming method, wherein the titanium compound A and the titanium compound B satisfy the following conditions.
Condition (1): RA <RB
Condition (2): DA <DB
Condition (3): RA ≦ 12.0
(Where RA and RB are the powder resistivity LogE (Ω · cm) when the applied voltage of the titanium compound A and the titanium compound B is 1.0 ^3.8 (V / cm), DA and DB are the titanium compound A and The volume average particle diameter (nm) of the titanium compound B is shown.)
Condition a: Pa ≦ 7
Condition b: Pb ≦ 40
Condition c: Pc ≧ 50
(Wa is the content (wt%) of titanium compound A, WB is the content (wt%) of titanium compound B, and a is the ultrasonic vibration (output 20 W, frequency: 20 kHz) in the toner dispersion. The amount of titanium compound desorbed from the toner particles when given for a minute, b is the amount of titanium compound desorbed from the toner particles when ultrasonic vibration (output 60 W, frequency: 20 kHz) is given for 30 minutes in the toner dispersion, and c is a and b indicate the amount of fine particles remaining on the toner particles after desorption, and Pa = 100 × a / (WA + WB), Pb = 100 × b / (WA + WB), and Pc = 100 × c / (WA + WB). is there.) In the developer for developing an electrostatic latent image, which includes a toner including at least toner particles and an external additive, and a carrier.
The toner includes at least toner particles and an external additive excluding silica ,
The toner particles have a volume average particle size of 4 μm to 8 μm, a GSD showing a volume particle size distribution of 1.23 or less, and a shape factor SF1 of 110 to 140,
The developer for developing an electrostatic latent image, wherein the titanium compound A and the titanium compound B satisfy the following conditions.
Condition (1): RA <RB
Condition (2): DA <DB
Condition (3): RA ≦ 12.0
(Where RA and RB are the powder resistivity LogE (Ω · cm) when the applied voltage of the titanium compound A and the titanium compound B is 1.0 ^3.8 (V / cm), DA and DB are the titanium compound A and (It is the volume average particle diameter (nm) of the titanium compound B.)
Condition a: Pa ≦ 7
Condition b: Pb ≦ 40
Condition c: Pc ≧ 50
(Wa is the content (wt%) of titanium compound A, WB is the content (wt%) of titanium compound B, and a is the ultrasonic vibration (output 20 W, frequency: 20 kHz) in the toner dispersion. The amount of titanium compound desorbed from the toner particles when given for a minute, b is the amount of titanium compound desorbed from the toner particles when ultrasonic vibration (output 60 W, frequency: 20 kHz) is given for 30 minutes in the toner dispersion, and c is a and b indicate the amount of fine particles remaining on the toner particles after desorption, and Pa = 100 × a / (WA + WB), Pb = 100 × b / (WA + WB), and Pc = 100 × c / (WA + WB). is there.)

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